HR: 1340h
AN: SM33A-1114    [Abstracts]
TI: EMIC scattering of relativistic electrons at geosynchronous orbit: an event study
AU: * Friedel, R H
EM: friedel@lanl.gov
AF: Los Alamos National Laboratory, ISR1: Space Science and Applications, MS D466, Los Alamos, NM 87545, United States
AU: Aasnes, A
EM: aasnes@rssd.esa.int
AF: ESA-ESTEC, Science Operations Department Keplerlaan 1, Noordwijk, 2201AZ, Netherlands
AU: Gary, S P
EM: pgary@lanl.gov
AF: Los Alamos National Laboratory, ISR1: Space Science and Applications, MS D466, Los Alamos, NM 87545, United States
AU: Varotsou, A
EM: athina@lanl.gov
AF: Los Alamos National Laboratory, ISR1: Space Science and Applications, MS D466, Los Alamos, NM 87545, United States
AU: Cayton, T E
EM: tcayton@lanl.gov
AF: Los Alamos National Laboratory, ISR1: Space Science and Applications, MS D466, Los Alamos, NM 87545, United States
AU: Christensen, R A
EM: rchristensen@lanl.gov
AF: Los Alamos National Laboratory, ISR1: Space Science and Applications, MS D466, Los Alamos, NM 87545, United States
AU: Shprits, Y
EM: yshprits@atmos.ucla.edu
AF: UCLA, Department of Atmospheric and Oceanic Sciences 7127 Math Sciences, Los Angeles, ca 90095, United States
AB: We present here detailed observations of a relativistic electron dropout event observed on August 4, 2002 by spacecraft LANL-97a. The observations where in the post-noon sector and coincided with observations of a plasma plume, which is one of the necessary conditions that enables EMIC resonance interactions with relativistic (> 500keV) electrons. Comparisons of the evolution if the pitch angle distributions of these energetic electrons with theoretical modeling of the evolution of an energetic particle distribution in the presence of pitch angle diffusion due to EMIC waves showed rough consistency: the loss of particles near the loss cone affects a wider range of near-parallel electrons for higher energy particles, and the loss is relatively quick, occurring over 10's of minutes, – both these effects are observed in the data.// We attempt here to fill in the last piece of evidence for an EMIC loss mechanism: determination of the presence of the waves. Since there are no direct wave measurements on the LANL geosynchronous spacecraft, we intend to use an indirect method by estimating the potential instability and growth rates of EMIC waves based on the detailed observation of the particle distribution function of the ring current ions that need to support EMIC wave growth.
DE: 2716 Energetic particles: precipitating
DE: 2720 Energetic particles: trapped
DE: 2730 Magnetosphere: inner
DE: 2772 Plasma waves and instabilities (2471)
DE: 2774 Radiation belts
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting